The properties that logd responds to are:

name                       type default  description
logd.auditd                 bool  true   Enable selinux audit daemon
logd.auditd.dmesg           bool  true   selinux audit messages duplicated and
                                         sent on to dmesg log
logd.klogd                  bool depends Enable klogd daemon
logd.statistics             bool depends Enable logcat -S statistics.
ro.config.low_ram           bool  false  if true, logd.statistics & logd.klogd
                                         default false
ro.build.type               string       if user, logd.statistics & logd.klogd
                                         default false
persist.logd.logpersistd    string       Enable logpersist daemon, "logcatd"
                                         turns on logcat -f in logd context
persist.logd.size          number 256K   default size of the buffer for all
                                         log ids at initial startup, at runtime
                                         use: logcat -b all -G <value>
persist.logd.size.main     number 256K   Size of the buffer for the main log
persist.logd.size.system   number 256K   Size of the buffer for the system log
persist.logd.size.radio    number 256K   Size of the buffer for the radio log
persist.logd.size.event    number 256K   Size of the buffer for the event log
persist.logd.size.crash    number 256K   Size of the buffer for the crash log

NB:
- number support multipliers (K or M) for convenience. Range is limited
  to between 64K and 256M for log buffer sizes. Individual logs override the
  global default.